Try not to overthink this. I agree with the poster who said to just write him a one liner. The thing about social media is that people are balancing a lot of relationships. I find that hard to deal with myself because I really prefer a few close relationships than the many that we can have with social media.

I COMPLETELY understand what you mean, Franner! I completely agree with what all the other wise, wonderful posters have already wisely said better than I ever could! Try not to think too much about it! If you DO want to restart contact with him I completely agree with what saidso has already wisely suggested about just writing something casually! Even a simple "How are oyu doing? It's been a while!" should be enough! You can always clarify later in the discussion those things you've just mentioned it! That's just my opinion of course, but perhaps he's just been busy or has had other problems! It doesn't necessarely have ANYTHING to do whith you or how you behaved! Just try it out and see how it goes! Let us know how things are going for you, ok? WE ALL CARE ABOUT YOU! THAT'S A PROMISE! I PROMISE YOU ALL OF THAT BECAUSE IT IS TRUE! PLEASE REMEMBER ALL OF THAT AS MUCH AS YOU POSSIBLY CAN BECAUSE IT IS TRUE! THAT'S A PROMISE! WE ALL CARE ABOUT YOU! THAT'S A PROMISE! WISH YOU GOOD LUCK! Let us know how things are going, ok? WE DO CARE! THAT'S A PROMISE! Sending many kind, safe, sweet, warm and WONDERFUL hugs to you, Franner, JUST LIKE YOU ARE!

like someone mentioned, not everyone checks and responds to messages in their inboxes.
maybe he didn't respond to your message because he felt it crossed a boundary (something which you didn't know )
maybe someone else said something which crossed a boundary and he left the site for a while
maybe he just had a life and was too busy to hit the site (it happens..things pile up and you don't go to the computer)

leave it. in time he'll check the box or not.

see him on line post something like good to see you. if it sparks interest good...